Yes, the more you post the message, the quicker it will be answered. It depends on the specific game but since most games for RISC OS are old, probably they're all playable - most of the decent ones needed SA/RO3.7+ patching. As for titles, try looking at Acorn Arcade for freeware/PD stuff.

EDIT: edited because I got the website wrong. I'll check it and post another...

For the old floppy-based games, A3000 (RISC OS 2) or A3010 (RISC OS 3) would seem good choices. If you can find a school chucking a 3020, that's good because they had more RAM and hard drives too, if memory serves.

The later machines run the more complex games of course, but it sounds like you're interested in the really early ones (late 80s, early 90s).

For the old floppy-based games, A3000 (RISC OS 2) or A3010 (RISC OS 3) would seem good choices. If you can find a school chucking a 3020, that's good because they had more RAM and hard drives too, if memory serves.

The later machines run the more complex games of course, but it sounds like you're interested in the really early ones (late 80s, early 90s).

Very true (although it was 800kb). The 3010 onwards introduced the 1.6Mb disc size. That said, there were very few games produced on 1.6Mb discs because all the "Archimedes" series (A310/320, A410/420/440 and possibly A540) came with the low density drives. As a result, games companies tended to release their games on a pile of low density discs. Even later titles like Dune2 (lots of floppies!) was on LD I think, but I could be wrong on that example. Drifter from 4D (one of their last titles) was on 1.6Mb disc I think (again, I could be wrong), and I know our games were on 1.6Mb discs, but all the older ones were low density AFAIK.